1. Field of the invention
This invention relates generally to a temperature probe and, more particularly, to a temperature probe employing a resistive temperature element mounted within a protective housing by a thermally conductive material to provide a fast thermal response time.
2. Discussion of the Related Art
Temperature probes are used in many applications for sensing the temperature of a solid, liquid or gas. For example, temperature probes are used in certain laser systems to detect the temperature of hydrogen peroxide (BHP) used in the generation of the laser beam. Other applications include medical, pharmaceutical, food, chemical, aerospace and industrial applications. In certain applications, it is important to measure the temperature accurately and very quickly.
Different classes of temperature sensors are known in the art to measure temperature. One class of temperature sensors employs resistive elements, well known to those skilled in the art. As the temperature of the element increases or decreases, the resistance of the element also increases or decreases providing an indication of the temperature change. A voltage signal applied to the element is measured to give a reading of the resistance, and thus the temperature.
Known temperature probes that employ resistive elements typically have a response time of seven seconds or more. Particularly, when the temperature of the environment that the sensor is sensing changes, the sensor does not give the exact temperature reading for the change until more than seven seconds later. The probe response time is defined herein as the time it takes the temperature sensor to respond through 63.2% of the total temperature change. This slow of a response time is unacceptable in many applications. The slow response time can be attributed to the fact that the resistive element is mounted within a protective housing and air forms between the element and the housing.
In accordance with the teaching of the present invention, a temperature sensor employing a resistive temperature element is disclosed that has a faster response time than those sensors known in the art. The sensor includes an outer protective housing in which the resistive element is mounted. In one embodiment, the housing is a cylindrical tube made of a thermally conductive material. The element is mounted at one end of the housing, and signal wires extend through the housing and out of an opposite end of the housing. The element is mounted to an inside surface of the housing by a thermally conductive potting material. Therefore, changes in temperature received by the housing are quickly transferred to the element through the potting material giving a quick temperature response time.
Additional objects, advantages and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.